1. Field of the Invention
This invention relates to a door closer. More particularly, this invention relates to a door closer which may be secured to a door or a door frame and which interacts with the door that is served by it.
2. Background Information
French Patent No. 1,510,056 discloses a door closer that is provided with a slide rail linkage. One end of an arm of the slide rail linkage is connected to the door closer that is located on the door panel, and the other end of the arm is mounted so that it slides in a rail on the door casing (came or frame). The door-closer-end side of the arm is connected with a drive shaft of a gear train that is coupled to a spring system. The gear train consists of specially shaped geared cam disks with a pitch profile that results from different segmentally constant radii of the geared cam disks.
The one geared cam disk is connected with the end of the arm by means of the output shaft of the door closer, and the other geared cam disk is connected with a pinion of the door closer that is engaged in a rack, which pinion moves the rack against or with the bias of a spring of the spring system.
When the door panel of the door is opened, this spring is stretched, which supplies the closing moment required to close the door. By means of the varying pitch curve of the two geared cam disks, the lever arm of the arm that varies with the opening angle of the door panel is counteracted, so that the torque required to open and close the door has a defined characteristic over the opening angle, in particular if the objective is to achieve a decreasing opening moment.
In practice it has been shown that the specially configured geared cam disks, with their pitch curve profiles that are different in each segment, are difficult, time-consuming and expensive to manufacture and require special gearing geometries.
These special gearing geometries must also be different for all geared cam disk combinations and for all geared cam disk configurations, as a function of the radii that change from one segment to the next. These configurations are extremely difficult, time-consuming and expensive to manufacture.
European Patent No. 0 856 628 A1 discloses a door closer, the drive shaft of which is connected with an eccentrically mounted gear wheel. This gear wheel meshes with its gear teeth in a gearing area that runs in a straight line and at an angle and is located inside a piston that interacts with a spring. As the drive shaft rotates, the resulting lever arms therefore have different effective lengths. Therefore the force and torque curve also changes.
The object of the invention is to improve a door closer as described above so that, while avoiding the disadvantages described above, a simple, space-saving construction is achieved that can easily be designed to achieve the desired torque curves over the opening angle of the door panel.
The invention teaches that this object can be accomplished as disclosed in a particularly simple manner using substantially standard gear wheels in a gear train according to one aspect of the invention.
The dependent claims describe additional advantageous embodiments of the invention.
The invention teaches that the force-torque curve that varies over the opening angle of the door, both during the opening and closing, can be influenced by means of a device that has a translation ratio that varies over the opening angle, which effect is achieved by eccentrically located gear wheels that have a circular gear rim and can be manufactured easily and economically.
The invention therefore teaches that the gear train, which has a translation ratio that varies over the opening angle of the door, has a first and a second gear wheels that mesh with each other, and each of these gear wheels is realized in the form of a circular gear rim, and which, while retaining their axial distance from each other, are mounted eccentrically with respect to their centers, and the first gear wheel of which is connected with an output shaft and the second gear wheel of which is connected coaxially with the center of motion with the gear wheel that is engaged with the rack that is coupled with the spring system, whereby the axis of rotation of the output shaft runs through the center of motion of the first gear wheel, and all of the above elements are arranged so that the eccentricity of the gear wheels that results from the center of a gear wheel and the new center of motion is point-symmetric to their pitch point.
The invention teaches a simple method to determine the torque curves by a choice of the eccentricity, the pitch circle diameter and the resulting distance between the axes of rotation of the two gear wheels. The result is a wide range of potential translation ratios and thus potential adaptations to desired torque characteristics over the opening angle of the door, without requiring specially fabricated geared cam disks. Instead, the invention teaches that it is possible to use commercially available gear wheels, which significantly reduces fabrication costs. The gear wheels can also have a standard gearing.
In other words, gear wheels with standard gear teeth can be used in one embodiment of the invention.
The magnitude of the eccentricity is described by the ratio of the eccentricity to the base diameter. In particular, this ratio should not exceed a value of 0.137 for gearings that are in compliance with DIN (German Industrial Standard) 867.
In one embodiment of the invention, the door closer a is realized in the form of a top-mounted door closer, with an effective lever arm that varies over the range of rotation between a first connection point of the rotational door panel of the corresponding door and an additional connecting point outside the door panel, which lever arm is engaged with the output shaft.
Thus, the door closer may be mounted at the top of the door frame or similarly near the ceiling structure where the door is installed.
The effective lever arm is preferably formed by a slide rail linkage or a toggle linkage.
Alternatively, the door closer can also be realized in the form of a floor-mounted (or bottom-mounted) door closer, in which the output shaft interacts with the bearing of the door panel.
The above-discussed embodiments of the present invention will be described further hereinbelow with reference to the accompanying figures. When the word xe2x80x9cinventionxe2x80x9d is used in this specification, the word xe2x80x9cinventionxe2x80x9d includes xe2x80x9cinventionsxe2x80x9d, that is, the plural of xe2x80x9cinventionxe2x80x9d. By stating xe2x80x9cinventionxe2x80x9d, the Applicant does not in any way admit that the present application does not include more than one patentably and non-obviously distinct invention, and maintains that this application may include more than one patentably and non-obviously distinct invention. The Applicant hereby asserts that the disclosure of this application may include more than one invention, and, in the event that there is more than one invention, that these inventions may be patentable and non-obvious one with respect to the other.